Top Level) General population can only verify their own votes
Mid Level) Counties can tally their county only
Low Level) States can tally up their states only
Ground Level) Federal government can tally up all votes.
The blockchain ledger will allow everyone to see votes without knowing individuals. To get name and location and other data, you need to be at a lower level.
If that's the case, it would be evidence that an individual voted for a specific candidate. This is, essentially, proof for anyone who'd want to purchase votes.
If they can't see who they voted for, they'd need some alternative way to verify that their vote counted for the candidate they wanted to vote for, without actually disclosing who that candidate is. Which would add some complexity to the solution.
To solve the issue of first voters (when there would be no other valid hashes for their printout) simply seed all candidates with a billion votes to start. Which hash is real and which is 'fake' is irrelevant since all that matters is the sum total of which we know 1 billion are to be removed.
The only other way to forge votes would be to invent new people that don't really exist, or maybe piggyback on recently deceased people. These are both problems that should be fairly straightforward to address if you have decently efficient administrations keeping track of things.
> The only other way to forge votes would be to invent new people that don't really exist
Exactly.
> straightforward to address
The question is how? I don't think it's considered that straightforward in blockchain voting circles.
The sums of the polling stations should equal the district.
The sums of the districts should equal the state.
The sums of the states should equal the nation.
I have to say it also makes me wonder what in the world darpa is thinking. Modern technology possible, somewhat trivially, elections that would be nearly impossible to fake in any way, shape, or form. And I'm certain this isn't exactly a secret to darpa.